The invention is concerned with disposable diapers and incontinent articles having refastenable mechanical closures and is specifically concerned with improvements in fit and closure stability.
Conventional commercial disposable diapers and adult incontinent products typically use pressure-sensitive adhesive (PSA) fastening tabs to close the diaper. Typically these PSA fastening tabs extend beyond the side edge of the diaper at a first ear or corner portion and attach to an opposing ear or corner portion as the opposing ears are overlapped in placing the diaper around the user. As such, the PSA fastening tab is permanently attached at a "manufacturers end" to one ear directly adjacent the side edge of that ear and refastenably attached at an inward location on the opposing ear or corner portion by a free end of the PSA fastening tab.
An improvement on the above basic adhesive closure system is the inclusion of a secondary pair of closure elements, which also engage when the two opposing ears are overlapped. This so-called "inner fastening means" is generally formed by placing a fastening element on an inner face the first ear, which engages with a corresponding or matched fastening surface or element on the outer face of the opposing ear. In this manner, the ears are directly secured to each other at their overlapping faces as well as by the conventional PSA fastening tab. The use of secondary closure elements is proposed in U.S. Pat. No. 4,699,622, which describes an elasticated diaper using an outer fastening tab and an inner fastening means. The conventional outer fastening tab extends from the longitudinal side edge at a first corner of the diaper. The inner fastening means is described as potentially including "VELCRO" strips, adhesive patches, buttons or snaps, but is preferably a mechanical fastening element placed on the outer face of the second opposing corner that engages with the topsheet nonwoven forming the inner face of the first corner. Specific improvements to the arrangement in U.S. Pat. No. 4,699,622 are described in U.S. Pat. No. 5,019,072, where the inner fastening means is a specifically described pair of overlapping cohesive or peelable adhesive patches on both the first corners or ears and the second opposing corners or ears, which patches are positioned such that they overlap when the opposing ears or corners of the diaper are overlapped when attaching the outer adhesive fastening tabs. U.S. Pat. No. 5,066,289 describes an improvement of the preferred design in U.S. Pat. No. 4,699,622, by providing a specific foraminous substrate on the inner face of the first corner for use as the release tape for the outer pressure-sensitive adhesive fastening tab. This foraminous release tape increases the attachment effectiveness of a male mechanical inner fastening means located on the second opposing ear of the diaper. U.S. Pat. No. 3,610,244 also proposes secondary closure elements. The patent describes using a conventional PSA fastening tab on a first corner of the diaper. In addition the inner face of this first corner contacts a PSA patch located on the outside face of the second opposing corner when the two opposing corners are attached in an overlapping relation with the conventional PSA fastening tab. The four points of adhesive attachment are described as providing more secure fit for active babies.
Although use of a secondary closure on the overlapping corners provides improved fit by inhibiting rotational shifting of the overlapping corners of the diaper, each with respect to each other, either from wearer movement or forces from the elasticized portions of the diaper, these systems are often exceedingly complicated to manufacture, requiring up to eight separate adhesive or mechanical fastening elements per diaper.